The invention relates to a process in particular for sealing containers with a foil or the like material, whereby a heating facility with heating element is pressed onto the container which has a foil or the like laid on top of it. The present invention also relates to a device having a heating facility suspended from a cross head spanning two columns, below which heating facility the container with the foil or the like is situated.
It is common knowledge to the average man in the field that bodies can be moved by means of attractive or repulsive type magnets. Attractive type magnets draw bodies towards them, in that for example a carrier plate on which the body to be moved is situated is drawn with the body to another plate herein called a counterpart. This is brought about by applying currents of different polarity to the plates in question. In the case of repulsive type magnets on the other hand both the carrier plate and counterpart, a fixed plate, exhibit the same polarity so that they repell each other.
In the case of conventional sealing devices, the raising of the heating element takes place either by means of a hydraulic or pneumatic drive. These machines are of a size conceived for large throughputs. For this reason they are as a rule useable only in industrial production lines in which a large number of, for example, containers, has to be sealed in a particular unit time.
Also known are manually operated sealing devices, in which the heating element is lowered onto the container to be sealed via a bracket and hinge. This machine is also available in a small size for example for individual production purposes. It suffers, however, the disadvantage that neither the duration nor the magnitude of applied pressure can be kept constant, so that as a result there is non-uniformity in the quality of the seal. In addition they lower the operational and workplace safety. Furthermore, a pressure of only approximately 100 kg can be generated with these devices.
In the case of machines involving the movement of a pressure-foot or the like, repulsive type magnets are normally used. If the pressure provided by such a machine is to remain constant on removing carrier plate and other plate between which the electromagnetic field is created, the raising facility must be of a particular size or the voltage applied must be raised continuously. Consequently machines with repulsive type magnets occupy a large amount of space and are complicated in construction.
Attractive type magnetics, the advantage of which lies especially in the reduction of the distance between for example a magnet plate and a carrier plate on going into service, have up to now found no application in the technology of machines operating on the principle of pressure.